Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$189.66	4.355%	$197.9197	$197.92	$197.90	$197.90
Purchase #2	$146.81	4.671%	$153.6675	$153.67	$153.65	$153.70
Purchase #3	$51.51	9.245%	$56.2721	$56.27	$56.25	$56.30
Purchase #4	$103.93	7.659%	$111.89	$111.89	$111.90	$111.90
Purchase #5	$185.43	10.172%	$204.2919	$204.29	$204.30	$204.30
Purchase #6	$119.31	3.667%	$123.6851	$123.69	$123.70	$123.70
Purchase #7	$173.49	13.458%	$196.8383	$196.84	$196.85	$196.80
7 purchase totals =	$970.14		$1,044.5646	$1,044.57	$1,044.55	$1,044.60